Efficient encoding of natural optic flow

Calow, Dirk; Lappe, Markus

doi:10.1080/09548980802368764

Cited by 15 publications

(24 citation statements)

References 35 publications

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“…Visual inspection reveals this to be due to different peak locations across individual participants rather than within. Some of the resulting distribution patterns (e.g., participant S3, Figure 7) resemble the T-shape previously reported in natural gaze behavior (Calow and Lappe, 2008;'t Hart et al, 2009). The T-shaped pattern is thought to represent gaze behavior during navigation, the T-trunk resulting from gaze directed toward the terrain immediately ahead, perhaps to verify navigability, and the T-bar representing gaze directed further up and looking toward the sides, perhaps to register the surroundings or to plan further ahead.…”

Section: Gaze Distribution (Eye-in-head)supporting

confidence: 79%

“…For the “T-shape” previously described in the RW ( Calow and Lappe, 2008 ; ’t Hart et al, 2009 ), we find a trend to an interaction between world and sector, so we cannot exclude that differences between VR and RW will start to emerge when more sophisticated measures or more difficult terrain (as compared to the smooth floor surface of an office building) are concerned. Explicitly modeling difficult and irregular terrain in VR will therefore become an interesting line for further research (cf.…”

Section: Discussionmentioning

confidence: 59%

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Gaze During Locomotion in Virtual Reality and the Real World

2021

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How vision guides gaze in realistic settings has been researched for decades. Human gaze behavior is typically measured in laboratory settings that are well controlled but feature-reduced and movement-constrained, in sharp contrast to real-life gaze control that combines eye, head, and body movements. Previous real-world research has shown environmental factors such as terrain difficulty to affect gaze; however, real-world settings are difficult to control or replicate. Virtual reality (VR) offers the experimental control of a laboratory, yet approximates freedom and visual complexity of the real world (RW). We measured gaze data in 8 healthy young adults during walking in the RW and simulated locomotion in VR. Participants walked along a pre-defined path inside an office building, which included different terrains such as long corridors and flights of stairs. In VR, participants followed the same path in a detailed virtual reconstruction of the building. We devised a novel hybrid control strategy for movement in VR: participants did not actually translate: forward movements were controlled by a hand-held device, rotational movements were executed physically and transferred to the VR. We found significant effects of terrain type (flat corridor, staircase up, and staircase down) on gaze direction, on the spatial spread of gaze direction, and on the angular distribution of gaze-direction changes. The factor world (RW and VR) affected the angular distribution of gaze-direction changes, saccade frequency, and head-centered vertical gaze direction. The latter effect vanished when referencing gaze to a world-fixed coordinate system, and was likely due to specifics of headset placement, which cannot confound any other analyzed measure. Importantly, we did not observe a significant interaction between the factors world and terrain for any of the tested measures. This indicates that differences between terrain types are not modulated by the world. The overall dwell time on navigational markers did not differ between worlds. The similar dependence of gaze behavior on terrain in the RW and in VR indicates that our VR captures real-world constraints remarkably well. High-fidelity VR combined with naturalistic movement control therefore has the potential to narrow the gap between the experimental control of a lab and ecologically valid settings.

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Section: Gaze Distribution (Eye-in-head)supporting

confidence: 79%

Section: Discussionmentioning

confidence: 59%

Gaze During Locomotion in Virtual Reality and the Real World

2021

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“…One of the insights from the observations in this study is that the stimulus input to the visual system is critically dependent on both the movement of the body and the gaze sampling strategies, especially in the case of motion stimuli. A similar point was made by Calow and Lappe (Calow & Lappe, 2008). Gaze patterns in turn depend on behavioral goals.…”

Section: Cortical Involvement In the Perception Of Optic Flowsupporting

confidence: 60%

“…A u t h o r M a n u s c r i p t D r a f t movements during natural locomotion determine the actual flow patterns on the retina. There has been some exploration of retinal motion patterns by measuring eye and head movements during locomotion (Einhäuser et al, 2007;Calow & Lappe, 2008). However, those measurements focused on the statistics of retinal flow, rather than the time-varying evolution of the signals.…”

Section: Introductionmentioning

confidence: 99%

Retinal optic flow during natural locomotion

Matthis

Muller

Bonnen

et al. 2020

Preprint

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Here we examine the ways that the optic flow patterns experienced during natural locomotion are shaped by the movement of the observer through their environments. By recording body motion during locomotion in natural terrain, we demonstrate that head-centered optic flow is highly unstable regardless of whether the walker’s head (and eye) is directed towards a distant target or at the ground nearby to monitor foothold selection. In contrast, VOR-mediated retinal optic flow has stable, reliable features that may be valuable for the control of locomotion. In particular, we found that a walker can determine whether they will pass to the left or right of their fixation point by observing the sign and magnitude of the curl of the flow field at the fovea. In addition, the divergence map of the retinal flow field provides a cue for the walker’s overground velocity/momentum vector in retinotopic coordinates, which may be an essential part of the visual identification of footholds during locomotion over complex terrain. These findings casts doubt on the assumption that accurate perception of heading direction requires correction for the effects of eccentric gaze, as has long been assumed. The present analysis of retinal flow patterns during the gait cycle suggests an alternative interpretation of the way flow is used for both perception of heading and the control of locomotion in the natural world.

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“…Extension of a subspace algorithm led to a biologically plausible two-layered population encoding network for heading estimation that accommodates eye rotation and depth of field effects (Lappe and Rauschecker 1993). This approach led to insights about potential receptive field subunit structures, including circular arrangements promoting radial selectivity for heading estimation from optic flow (Beintema et al 2004;Calow and Lappe 2008).…”

Section: Optic Flow Stimulusmentioning

confidence: 99%

Receptive Field Dynamics Underlying MST Neuronal Optic Flow Selectivity

Page

Gaborski

et al. 2010

Journal of Neurophysiology

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Yu CP, Page WK, Gaborski R, Duffy CJ. Receptive field dynamics underlying MST neuronal optic flow selectivity. J Neurophysiol 103: 2794 -2807, 2010. First published March 24, 2010 doi:10.1152/jn.01085.2009. Optic flow informs moving observers about their heading direction. Neurons in monkey medial superior temporal (MST) cortex show heading selective responses to optic flow and planar direction selective responses to patches of local motion. We recorded MST neuronal responses to a 90 ϫ 90°optic flow display and to a 3 ϫ 3 array of local motion patches covering the same area. Our goal was to test the hypothesis that the optic flow responses reflect the sum of the local motion responses. The local motion responses of each neuron were modeled as mixtures of Gaussians, combining the effects of two Gaussian response functions derived using a genetic algorithm, and then used to predict that neuron's optic flow responses. Some neurons showed good correspondence between local motion models and optic flow responses, others showed substantial differences. We used the genetic algorithm to modulate the relative strength of each local motion segment's responses to accommodate interactions between segments that might modulate their relative efficacy during co-activation by global patterns of optic flow. These gain modulated models showed uniformly better fits to the optic flow responses, suggesting that coactivation of receptive field segments alters neuronal response properties. We tested this hypothesis by simultaneously presenting local motion stimuli at two different sites. These two-segment stimuli revealed that interactions between response segments have direction and location specific effects that can account for aspects of optic flow selectivity. We conclude that MST's optic flow selectivity reflects dynamic interactions between spatially distributed local planar motion response mechanisms.

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Efficient encoding of natural optic flow

Cited by 15 publications

References 35 publications

Gaze During Locomotion in Virtual Reality and the Real World

Gaze During Locomotion in Virtual Reality and the Real World

Retinal optic flow during natural locomotion

Receptive Field Dynamics Underlying MST Neuronal Optic Flow Selectivity

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